[jfrancis49]

Hello All,

I have been restoring a Beogram 4002 type 5513 turntable and have done a capacitor replacement and all the other electrical and mechanical adjustments I am able to. The very last thing is to adjust the tracking sensor. However I cannot get any response when I try to adjust it. And I do mean the sensor at the base of the tone and sensor arms. Meaning the carriage drive will not move forward, and no pulley rotation. Also I do not see a light at the sensor, but a voltage check across the bulb leads reads 20.75 DC. A continuity test doesn’t show that the bulb is functioning, no continuity. I have a spare sensor housing which I have put in place of the old one but the same story with that, no continuity.

So my question is, is the voltage to the bulb at 20.75 volts too low. Or are both bulbs bad and the continuity test shows me the filaments are broken in both sensor housings? My assumption is the bulbs have filaments.

Any thoughts would be appreciated.

John

 

[Mark-sf]

Both those bulbs are bad if you do not have continuity from them. If you want to confirm before ordering, this lamp is the same one that illuminates the 33 and 45 speed adjustment.

[jfrancis49]

Hello Mark,

Thank you for the post. I did have a lamp for the 33 and 45 speed adjustment, so I tried a continuity test on it and it showed no continuity. So I connected a 9V battery to it and it lit up. Not sure why my meter is not showing continuity. Crossing the leads does and my meter squeals like it should. Anyway I took the tracking sensor out of the BG 4002 and connected the leads to the 9 V battery, no light, bad bulb. I tried the other spare sensor I have and the bulb lights with the battery, so I will install that tomorrow and see if that takes care of it. Once again, thanks for your response.

John

[Mark-sf]

I should have been clearer regarding “continuity”. You will not see 0 ohms but there will be a resistance vs. an open circuit. If your meter is not Auto-Ranging, you may have to change to a higher range to observe this resistance which should be ~1K Ohms.

[AdamS]

In addition to the point above, some ‘continuity’ meters only beep when below a certain resistance. The filament of the lamp will have a resistance and if it happens to be above this point, then your meter won’t ‘beep’, giving the impression that there is an open circuit.

[jfrancis49]

Thank you Mark and Adam. Well, I learned something through this experience which is I didn’t think about bulb filament resistance as a factor in my thinking. The good news is I swapped out the tracking sensor today and it is working!

Lucky for me the issues related to this restoration have not required more than switching out a number of parts, soldering new components and adjustments to get this working. Serious trouble shooting is beyond my capabilities.

Thanks for your kind support!

John

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